Published: 18 Jun 2025

ICD9: 332      ICD10: G20      ICD11: 8A00

Parkinson's disease (PD) is a progressive neurodegenerative disorder that primarily affects movement.
It develops gradually, often starting with a barely noticeable tremor in one hand. While tremors are a common symptom, the disease can also cause stiffness, slowed movement (bradykinesia), and difficulty with balance.

Here's a breakdown of key aspects:

What Happens in the Brain:

Loss of Dopamine-Producing Neurons: The primary problem in Parkinson's disease is the death of neurons in a specific area of the brain called the substantia nigra. These neurons produce dopamine, a neurotransmitter crucial for controlling movement, coordination, and other functions like mood and motivation.
Dopamine's Role: Dopamine acts like a messenger, transmitting signals between nerve cells in the brain to coordinate muscle movement. When dopamine levels decrease due to the loss of these neurons, it disrupts the normal communication and leads to the characteristic motor symptoms of Parkinson's.
Lewy Bodies: Many people with Parkinson's also develop Lewy bodies – abnormal clumps of protein (primarily alpha-synuclein) that accumulate inside neurons. While the exact role of Lewy bodies in PD is still being researched, they are considered a pathological hallmark of the disease. They are not always present but are frequently found during autopsy.

Symptoms:

The symptoms of Parkinson's disease can vary from person to person, and the progression is different for everyone. Common symptoms include:

Motor Symptoms (related to movement):
Tremor: Involuntary shaking, often starting in the hand or fingers ("pill-rolling" tremor). It typically occurs when the limb is at rest.
Bradykinesia: Slowness of movement. This can make simple tasks like getting dressed or walking difficult and time-consuming.
Rigidity: Stiffness in the limbs and trunk. Muscles may feel tight and achy.
Postural Instability: Problems with balance and coordination, leading to an increased risk of falls.
Gait Disturbances: Shuffling walk, reduced arm swing.
Speech Changes: Soft speech (hypophonia), slurred speech, monotone voice.
Writing Changes: Small, cramped handwriting (micrographia).
Swallowing Difficulties (Dysphagia): Can lead to choking or aspiration.
Non-Motor Symptoms: These symptoms can be present years before the motor symptoms and significantly impact quality of life.
Sleep Disturbances: Insomnia, restless legs syndrome, REM sleep behavior disorder (acting out dreams).
Cognitive Impairment: Problems with memory, attention, and executive function (planning, decision-making). Can progress to dementia in some cases.
Mood Disorders: Depression, anxiety, apathy.
Autonomic Dysfunction: Constipation, bladder problems, orthostatic hypotension (low blood pressure upon standing), excessive sweating.
Loss of Smell (Anosmia): Often an early symptom.
Fatigue: Persistent tiredness.
Pain: Various types of pain, including muscle aches, joint pain, and nerve pain.

Causes:

The exact cause of Parkinson's disease is unknown, but it is likely a combination of genetic and environmental factors.

Genetics: While most cases of Parkinson's are not directly inherited, some genes have been identified that increase the risk. These genetic links are stronger in early-onset PD (before age 50).
Environmental Factors: Exposure to certain pesticides, herbicides, and heavy metals has been suggested as possible risk factors. Head trauma is also being studied.
Age: Age is the biggest risk factor. The risk of developing Parkinson's increases with age.
Lewy Bodies: As mentioned above, these are often found in the brains of those with PD but their exact role in causing the disease is still being investigated.

Diagnosis:

There is no single test to diagnose Parkinson's disease. Diagnosis is based primarily on a neurological examination, a review of the patient's medical history, and an assessment of their symptoms.

Neurological Exam: A neurologist will assess motor skills, balance, coordination, reflexes, and cognitive function.
Medical History: The doctor will ask about symptoms, medications, and family history.
DaTscan: A DaTscan is a type of brain imaging that can help visualize dopamine transporters in the brain. It can help differentiate Parkinsonian syndromes from other conditions that may mimic PD, such as essential tremor. However, it cannot definitively diagnose PD.
Response to Medication: The neurologist may prescribe levodopa (a medication that increases dopamine levels) to see if it improves the symptoms. A positive response to levodopa supports the diagnosis of Parkinson's disease.

Treatment:

There is currently no cure for Parkinson's disease, but there are treatments that can help manage the symptoms and improve quality of life.

Medications:
Levodopa: Converts to dopamine in the brain. Often combined with carbidopa (to prevent levodopa from breaking down before it reaches the brain). It's very effective but can cause side effects over time, such as dyskinesias (involuntary movements).
Dopamine Agonists: Mimic the effects of dopamine in the brain. Less effective than levodopa but may be used in early stages or in combination with levodopa.
MAO-B Inhibitors: Prevent the breakdown of dopamine in the brain.
COMT Inhibitors: Help levodopa work longer by preventing its breakdown.
Amantadine: Can help reduce dyskinesias.
Anticholinergics: Can help reduce tremor, but have many side effects.
Deep Brain Stimulation (DBS): A surgical procedure in which electrodes are implanted in specific areas of the brain. These electrodes deliver electrical impulses that can help control motor symptoms. DBS is typically considered for people with PD who have significant motor fluctuations or dyskinesias that are not adequately controlled by medication.
Other Therapies:
Physical Therapy: Helps improve balance, coordination, and strength.
Occupational Therapy: Helps people adapt to their limitations and perform daily tasks.
Speech Therapy: Helps with speech and swallowing problems.
Exercise: Regular exercise is crucial for maintaining mobility, strength, and balance. It can also improve mood and cognitive function.
Nutrition: A healthy diet is important for overall health and can help manage constipation and other non-motor symptoms.
Support Groups: Connecting with others who have PD can provide emotional support and practical advice.

Prognosis:

Parkinson's disease is a progressive condition, meaning the symptoms worsen over time. The rate of progression varies widely from person to person. While PD can significantly impact quality of life, most people with Parkinson's can live for many years with appropriate treatment and support. PD itself is rarely fatal, but complications such as falls, pneumonia, and swallowing difficulties can contribute to mortality.

Key Takeaways:

Parkinson's Disease is a progressive neurodegenerative disorder that affects movement and other functions.
It's caused by a loss of dopamine-producing neurons in the brain.
Symptoms vary but commonly include tremor, slowness of movement, rigidity, and postural instability. Non-motor symptoms are also common and can be debilitating.
There's no cure, but treatments can manage symptoms and improve quality of life.

It is important to note that this information is for general knowledge and does not constitute medical advice. If you are concerned about Parkinson's disease, please consult with a qualified healthcare professional for diagnosis and treatment.